Do the expansion cards need to be separated from the base deck, and how do you tell which set a card belongs to?

Question

Accepted Answer

No separation is needed, since all cards are usable in the base game. Each card has a code at the bottom middle: base cards start with K, Guild Master's Revenge cards with GMR, and Boss Battles cards with BB.

Keep the Heroes Out!

Do the expansion cards need to be separated from the base deck, and how do you tell which set a card belongs to?